I'll make this brief..
I'm a 30 ya female and I don't know tons about mechanics.
I shopped around and finally payed cash for a 1998 Subaru Legacy with almost 200k.
The carfax looks great. One owner. regular maintenance.
When I was driving it home I noticed the steering wheel vibrating, quite violently, and I think the seats. The car also wanders way to the right when I take my hands off the wheel... what could this be? (btw, carfax states that there are no car accidents on record for the car.)

You don't have to read on from here if you don't wanna... the problem below should be fixed in theory, as long as the dealership isn't lying more.

So I started to drive it on the freeway and the temp went alllll the way up.
Took it to private mechanic. Hydrocarbons found in coolant system. After 2 days of dealing with the dealerships lies, I threatened them (in my state DMV deals with lemons sold with no warranty after 3 days or less). They agreed to replace head gaskets. I'm going to take it back to my private mechanic after they "fix" it to make sure they did and ask tomorrow for a work order in writing.

Could be a bad radial as well. You could have your mechanic swap the front tires left to right to see if it changes the direction of pull. Then, you may want to get the tires balanced, check for a bent wheel and get the alignment checked.

On a side note, what many people do not realize is a carfax report is a bogus piece of paper. If it was in an accident and not reported to the insurance company, it will not appear on the carfax. Essentially, it scratches the surface on the cars history. If the previous owner took it to the dealer the whole time they had it then you will have a good idea of its maintenance history. I strongly believe the Carfax report is only available to aid in the selling of a vehicle. Have a trusted mechanic look over the entire car BEFORE buying. I have seen flawless Carfax reports and oversprayed bumpers, misaligned fenders, new radiators, etc.